For all we know, jawline and spatial reasoning share a gene somewhere. Human pattern recognition is far better than we give it credit for.

It's generally been proven that taller, more attractive people loosely correlate with better intellect or soft intelligence proxies. It doesn't even have to be genetic. It stands to reason that a healthy and well cared for childhood that leads to reaching a greater proportion of your potential height, could also potentially lead to you realising a greater degree of your mental potential too.